In modern laser processing, under some special circumstances, it is required for the laser processing to cut thin lines with a large aspect ratio, or cylindrical holes with a relatively large depth and a small aperture. For instance, in some cases, it requires to process a line with a depth of 0.5 mm and the width of only 0.05 mm. There are some other occasions where a cylindrical hole with a depth of 0.5 mm and an aperture of only 0.05 mm is required to process. Due to the aperture limit of the optical system, if the aperture is too small, sharp diffuse spots will appear during processing, and the laser energy is not enough. If the aperture is increased, then the processed thin lines or deep holes may not meet the size requirements.